The present invention relates to vehicle body closure panels with a counterbalancing hinge having a torque rod with end assemblies forming a pivot connection between the closure panel and vehicle body pillars.
Vehicle body closure members, such as a tailgate, are pivotally mounted between body side panels forming the pillars at the rear of the vehicle. The tailgate pivots about a hinge axis between a horizontal, open position and a vertical, closed position. Preferably, the mounting assemblies for the tailgate permit the tailgate to be removed, and this has been accomplished in a known construction when the tailgate is pivoted to a position between the fully open or fully closed position. For example, the tailgate may include hinge pins that extend outwardly along the hinge axis that removably connect into brackets carried on the truck body. When the tailgate is pivoted to a predetermined intermediate position, for example, 15° away from a fully closed position, at least one of the hinge pins slips through a slot in the connecting bracket as the tailgate is lifted at one end from the truck body.
Some of the tailgate mounting assemblies include a spring bias assist for assisting movement and counterbalancing the weight of a tailgate during opening or closing movements. One previously known mechanism in which a torque rod provides spring biasing between the tailgate and the body panel pillars carries the torque rod on assemblies that form the pivots for the tailgate. Since the torque rod forms a portion of the pivot assembly, the torque rod must be installed for the tailgate to pivot and thus complicates the assembly procedure. Moreover, the torque rod may require particularly configured ends that complicate production of the parts before assembly.
A previously known tailgate assembly may use hinge pin trunnions for pivoting and the torque rod is pre-formed and installed into the tailgate in a complex and intricate procedure. For example, during assembly of the tailgate, the stationary end of the rod has to be aligned with an aperture that exposes the end for attachment outside of the tailgate while the anchoring end is aligned with a reinforcement plate located inside the tailgate. All of the aligning must be performed while the torque rod is carried within the interior of the tailgate and the procedure may be difficult and time consuming. Moreover, numerous components are required to assemble the torque rod to the tailgate. Other types of springs used in place of the torque rod are difficult to install within the confines of tailgates made of inner and outer panels joined together before the hinge assembly is mounted. Moreover, such assemblies may be difficult to repair, and replacement parts are complex and expensive.
One previously known tailgate assembly uses an anchoring member that serves to rotationally ground one end of a torque rod within the interior of a tailgate. The anchoring member is mounted on a hinge bracket, which is attached to the tailgate, and extends into the interior of the tailgate through an aperture. The anchoring member can be a pinch block with a bore formed therein for receiving one end of the torque rod. The pinch block also has a torsion bar retainer, which is a cap fastened to the top of the pinch block by means of rivets or bolt, or the like. The torsion bar retainer, when secured to the top of the pinch block, serves to grounded or non-rotationally lock the torque rod to the pinch block. As a result, the pivoting of the tailgate causes the torsion bar to be subjected to torsional windup sufficient to produce assistance for a vehicle operator opening or closing the tailgate. One advantage of a design in which one end of the torsion bar is grounded within the tailgate is that, even if the torsion bar were to break, the pivoting function of the tailgate system and, for that matter, the retention of a tailgate upon a vehicle, will not be adversely affected by the breakage of the torsion bar. One weakness of this design, however, is that the torsion bar retainer cap is prone to bending and failing in response to the twisting to the torque rod held beneath it. Thus, the tailgate lift assist function provided by the assembly in which this design is used will be lost upon the failure of the torsion bar retainer.
Accordingly, a tailgate hinge assembly that includes a tailgate lift assist assembly in which an end of a torque rod is rotationally and reliably grounded within the interior of the tailgate is needed.